How to make google Chrome omnibar search sites permanent?

How to make google Chrome omnibar search sites permanent?

In google Chrome, when you have visited a site, say wikipedia.com, your can thereafter search the site directly from the omnibar by typing in a few letters then hitting tab. However, I noticed that after I clear my cache, Chrome does not remember the search autofills, and I once again have to visit the site manually for it to take effect.